Fork-tailed swift description

Named for its broad and deeply forked tail (2)(3)(4)(5)(6)(7), the fork-tailed swift (Apus pacificus) is a relatively large swift (2) with a rather slender body (3) and long, narrow, sickle-shaped wings (2)(3)(4)(8). When tightly closed, this species’ sharply forked tail looks rather spike-like (7).

The fork-tailed swift is mainly black (2)(4)(7)(9), while the species’ most striking feature is the conspicuous white band on its rump (2)(3)(4)(5)(7)(9). The dark feathers on the underparts are broadly white-fringed (2), and the throat has a white patch (3)(8)(9). The fork-tailed swift has dark brown eyes and a black bill (3)(6).

While the distinctive shape of the tail gives this species its common name, it is the feet that give the fork-tailed swift its scientific name. The genus name Apus comes from the Greek word ‘apous’, meaning ‘without feet’ (9). This description is, of course, not entirely accurate, as the fork-tailed swift does have feet, but its purplish legs and feet are very short (3)(6)(9). This species never settles voluntarily on the ground, spending most of its life in the air and only using its small feet to cling to vertical surfaces (9).

There are four recognised subspecies of fork-tailed swift (2)(5)(10), all of which differ slightly in size and pattern, particularly in terms of the rump and throat patterning (10).

The fork-tailed swift is known to make a buzzing, twittering sound (6), as well as long, hard, high-pitched screams, described as ‘skree-ee-ee’ or ‘shkree’ (6)(8)(11). Such shrill calls are particularly common in small parties and flocks close to breeding sites (3).

Related species

Fork-tailed swift biology

The fork-tailed swift is generally considered to be a migratory species, although not all of the subspecies necessarily migrate. Apus pacificus pacificus is a long-distance migrant, wintering in Indonesia and Australia between October and April, whereas the other three more southerly subspecies tend to be mainly resident, or only migrate short distances (2).

A gregarious species, the fork-tailed swift is generally found in large flocks (2), often mixing with other species of swift (6)(11). However, when foraging it is most commonly found in small groups of three to five birds (2). An aerial feeder (8)(9), the fork-tailed swift never voluntarily settles on the ground (9), and catches its insect prey while in flight (2)(9).

The type of prey taken varies with the location, but flies, termites and bees are among the insects recorded as part of the fork-tailed swift’s diet (2). The fork-tailed swift flies very fast as it forages (8), and it is known to make erratic flutters and turns when feeding (6), often being highly vocal (3).

The timing of the fork-tailed swift’s breeding season varies depending on location, occurring between March and May in Nepal, April to June in the Himalayas, and between June and August in Japan (2).

The fork-tailed swift’s nest is a half-cup made of vegetable matter which is stuck together using saliva (2). Saliva is also used to fix the nest to the sloping face of a cliff fissure or under the roof of a building (2)(3). The female fork-tailed swift lays a clutch of between one and three eggs, and both adults take part in all nest duties. The eggs are incubated for a period of 17 days, and the chicks fledge at about 40 days old (2). The fork-tailed swift returns to the same nest site year on year, simply rebuilding the nest when necessary (9).

Fork-tailed swift range

The fork-tailed swift breeds from Siberia eastwards through Asia (6)(9), including in China (3), the Himalayas, north-western Thailand, central Vietnam, Japan and the Philippines (12). A migratory species, the fork-tailed swift winters in Indonesia, Australia and New Guinea (6)(12). Although this species is a rare vagrant in Western Europe, it has been recorded as far west as Norway and Great Britain (9).

Each of the four subspecies of fork-tailed swift have slightly different ranges (2)(3), with their breeding ranges replacing each other from north to south. The more northerly breeding subspecies are known to winter further south than the most southerly breeding subspecies(5).

Species with a similar range

Fork-tailed swift habitat

Occurring from the low Arctic to the tropics, and from lowlands to high mountains, the fork-tailed swift can be found in a wide range of habitats (2)(3). It often occurs around towns and villages (2)(11), as well as in forested and open areas (4)(12), rocky regions, coastal zones (12), mountains and around lakes (11). The fork-tailed swift is also known to forage around cultivated areas (11), and it breeds in cliffs, caves and buildings (12). This species mainly winters in lowland areas, and in Japan the fork-tailed swift has been recorded at elevations of up to 3,000 metres (2).

Fork-tailed swift threats

Fork-tailed swift conservation

The fork-tailed swift is generally considered to be common throughout most of its breeding and wintering range (2), and as a result there are no known specific conservation measures currently in place for this species.

Authentication

Glossary

Genus

A category used in taxonomy, which is below ‘family’ and above ‘species’. A genus tends to contain species that have characteristics in common. The genus forms the first part of a ‘binomial’ Latin species name; the second part is the specific name.

Incubate

To keep eggs warm so that development is possible.

Subspecies

A population usually restricted to a geographical area that differs from other populations of the same species, but not to the extent of being classified as a separate species.

MacKinnon, J. and Phillipps, K. (2000) A Field Guide to the Birds of China. Oxford University Press, Oxford.

Chantler, P. (2000) Swifts: A Guide to the Swifts and Treeswifts of the World. A&C Black Publishers, London.

Grewal, B. and Harvey, B. (2003) A Photographic Guide to the Birds of India: And the Indian Subcontinent, including Pakistan, Nepal, Bhutan, Bangladesh, Sri Lanka, and the Maldives. Princeton University Press, New Jersey.

MobileReference (2009) The Illustrated Encyclopedia of European Birds: An Essential Guide to Birds of Europe. MobileReference, Boston.

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